Ignis Fatuus is a real world phenomena, known also as Will-o'-wisp and Jack-o'-lantern, where glowing lights are seen over marshy land, caused by ignited swamp gas and often attributed in folklore and mythology to mischievous spirits attempting to lead travelers astray.[1][2] The same folklore root is shared by the Blood Omen enemy class the Will-o-wisps.[BO1][3]

Ignis Fatuus is directly named as such in dialogue in Kain's first conversation with Moebius - which is accompanied by a 'vision' of the lanterns. After this, they are never spoken of again and are not acknowledged in either stage directions or dialogue. strategy guides likewise do not acknowledge them and they are only mentioned in passing in the Soul Reaver 2 prima guide as "burning braziers".[BO1][BO1-C5][BO1-C6][4]

The Ignis Fatuus lanterns seen in the Swamp in Soul Reaver 2 are notably extinguished in the Era following Blood Omen and are often accompanied at this time by other, more conventional fire-light lanterns. This perhaps suggests that they are somehow related to Vorador and are extinguished in periods beyond his death. Similarly Vorador's crows are absent from the era.[SR2][SR2-C5]

Though hinted to lead in a trail through the Termogent Forest to Vorador's Mansion, the Ignis Fatuus lanterns in Blood Omen actually follow a more complicated pattern. A line leads along the north of the western map area and heads into the eastern area - following the spiralling path around to the mansion - however just before it reaches the eastern map a secondary trail of lanterns branches off to the south west towards the three 'keep' dungeons. Presumably this serves to guide the player to visiting each of the keeps before pressing on towards the mansion. Though the lanterns in Blood Omen (and apparently Defiance) clearly lead to Vorador's Mansion it is unclear whether the lanterns are intended to lead anywhere in Soul Reaver 2 - their placement seems more intended to highlight certain pathways and buildings than to guide to any particular one, however if this was the case then they could well point to the Dark forge (or the time streaming chamber nearby). Although it is not featured in the Soul Reaver 2 swamp area, Vorador's Mansion - which would be off the map to the north east - could also be a potential candidate. The Defiance version is little more than a decorative addition outside the playable map area of Vorador's Mansion.[SR2][SR2-C3][SR2-C5][SR2-C7][SR2-C9][DEF][DEF-C8]

Ignis Fatuus notably undergo a subtle redesign between titles. Those seen in Blood Omen use human skulls, however those in Soul Reaver 2 and Defiance are bear fangs suggesting they are crafted from vampire skulls.[BO1][SR2][DEF]

The origin of the Ignis Fatuus is never discussed and their appearances would seem to associate them with Vorador and his mansion. However the vampiric nature of the later skulls and the potential association with the Dark Forge may suggest an older origin.[BO1][SR2][DEF] The green flames are also somewhat reminiscent of the Glyph magic seen in Blood Omen 2.[BO2]